1. Field of the Invention
The present invention relates to a rotary damper capable of sliding a sliding portion constituted of an rotary member radially along a basement portion and capable of adjusting the magnitude of a torque generated, and to a rotary damper generating a torque by narrowing a clearance between the outer surface of an oscillation member oscillated by the force of more than the regular amount generated by the rotation of a drive shaft and the inner peripheral surface of a chamber.
2. Description of Prior Art
Hereto in the past, when an hanging door or the like which are left open are closed, there have been problems in that colliding sounds are generated and a door or a door frame is broken because the door collides with the door frame by an abrupt door closing operation. In order to prevent such an abrupt door closing operation, a variety of dampers for braking the door closing operation have been proposed.
For example, as shown in FIG. 14, Japanese Patent Laid-Open No. 8-93312 discloses a fluid friction resistance type braking device for use on a door closer which comprises a rotary drum 34 fixed to a braking shaft 33, an adjustment screw 35 screwed to a base portion 31A fixed to a lid body portion 31B of a body of equipment 31, a movable drum 36 screwed to this adjustment screw 35 and capable of moving along a groove 31C of die lid body portion 31B and one way clutch 37 transmitting a one way only rotational operation to the braking shaft 33.
Moreover, as shown in FIG. 15, such a damper apparatus is mounted on a sliding door in such way that a pinion 13 attached to the braking shaft 33 is engaged with a rack 12 fixed to a guide rail member 11 of the door frame side. When the door closing operation is performed, the rotational operation of the pinion 13 is transmitted to the braking shaft 33 by the clutch 37 and the door closing operation is braked. On the other hand, when the door opening operation is performed, the transmission of the rotational operation of the pinion 13 to the braking shaft 33 is prevented by the clutch 37.
However, such a damper apparatus is constituted in such a manner that, by moving the movable drum 36 axially inside the body of equipment 31, the contact and slide area between the outer peripheral surface of the movable drum 36 and the inner peripheral surface of the rotary drum 34 is changed so as to adjust the magnitude of a generated torque. Accordingly, when the generated torque has to be adjusted low in the magnitude, it is necessary to minimize the contact and slide area of both the above described surf aces. In such a case, it is necessary to separate largely radial surfaces of the movable drum 36 and the rotary drum 34. As a result, there was a disadvantage that it was impossible to make a length of a damper main body in the axial direction short.
Furthermore, in the case when a door is abruptly closed, very high load temporarily operates the door. However, since the magnitude of the torque generated by the damper apparatus is a fixed quantity, it is impossible to absorb the above described high load, and enough damper effect cannot be obtained. As a result, the door closing operation is not braked, the problem arises that the generation of colliding noises and the breakdown of the door due to collision of the door to a door frame or the like is not preventable.
Hence, there has been a desire for a compact damper with a short radial length or a damper capable of absorbing an extremely high load which acts temporarily when the door is abruptly closed.
The rotary damper according to a first invention for solving the above described problem, wherein a housing with its inside provided with a chamber, a drive shaft with its base end side housed inside the chamber, a rotary member housed inside the above described chamber axially supported by the drive shaft and a viscous fluid filled inside the above described chamber are provided and a torque is generated by the rotation of the above described rotary member,
the rotary damper generating a torque by the rotation of the above described rotary member, wherein the above described rotary member is provided with a basement portion axially integrally rotatably supported by the above described drive shaft, a torque adjustor capable of making a relative movement by action of the external force of more than the regular amount while maintaining a fixed relationship with the above described drive shaft, a slide member arranged axially movably and having an outer surface complementary to a part of the inner peripheral surface of the above described chamber and a spring means for energizing the slide member against the above described torque adjustor, and
wherein, by relatively moving the above described torque adjustor against the above described drive shaft, the above described slide member is allowed to slide radially along the above described basement portion in such a manner as to change a radial clearance between the outer surface of the above described slide member and the inner peripheral surface of the above described chamber, thereby changing a rotary torque of the above described rotary member.
By allowing the slide member to slide along the base portion so as to control a radial clearance formed between its outer surface and inner peripheral surface, the torque generated based on the sheering resistance of the viscous fluid existing in this clearance can be changed and therefore no limitation is imposed in relation to the radial length of the damper main body.
The above described torque adjustor comprises an adjustment ring integrally rotatably attached to the above described rotary member and a cam member attached to the outer periphery of the adjustment ring, wherein the outer periphery of the above described adjustment ring and the inner periphery of a center hole of the above described cam member are engaged with a concave portion formed on the one and a convex portion on the other, wherein the concave portion and convex portion are constituted in such a manner that, when the external force of more than the regular amount acts on the above described cam member, the above described cam member is allowed to swing at the predetermined angle relatively against the above described adjustment ring and the above described drive shaft. In this way, the torque adjustor can be certainly arranged at the predetermined angle against the drive shaft.
By allowing the outer periphery of the cam member of the above described torque adjustor to take the shape of oval, the distance from the center of the cam member to each contact portion with the slide member and the cam member can be continuously displaced.
The above described cam member has a radial projection portion projected outside of the above described housing and provides an action portion for swinging the above described torque adjustor at the predetermined angle relatively against the above described drive shaft on the tip of the above described projection portion. In this way, the torque adjustor can be easily swung till the position of the predetermined angle.
The above described torque adjustor comprises the cam member attached integrally rotatably to the basement portion of the above described rotary member and an adjustment member engaged with the cam member, wherein the above described cam member has a cam surface comprising a slant surface on the outer periphery, a joining portion joined axially at one side with the above described rotary member and a wall portion formed axially at the other side, wherein the above described adjustment member has an action surface engaged with the wall portion of the above described cam member axially at an inner end portion, and wherein the above described cam surface and the above described action surface are constituted in such a manner that, when the external force of more than the regular amount acts on the above described adjustment member, the position of the portion engaged with the above described wall portion of the above described cam member of the above described action surface moves axially, thereby allowing the above described cam member to move along the above described drive shaft. In this way, the cam member can be certainly arranged along the drive shaft with the predetermined distance.
The adjustment member has an outer end portion projected outside of the above described housing and provides an action portion for moving the above described cam member along the above described drive shaft on the above described outer end portion. In this way, the cam member can be certainly moved to the predetermined position along the drive shaft.
The energization force of the above described spring means which is the predetermined centrifugal force acting on the above described slide member by the rotation of the rotary damper was, for example, set smaller than the centrifugal force generated when the number of revolutions of the drive shaft are increased with a high load temporarily acted on a hanging door or the like.
Because the centrifugal force generated in this way is allowed to become equal to or more than the energization force of the spring means, the slide members attempt to separate respectively from a state of being energized to the torque adjustor by opposing to the energization force of the spring means. As a result, the radial clearance formed between the outer surface of the slide member and the inner peripheral surface of the chamber can be temporarily made much narrower, thereby absorbing a temporal high load and allowing a full braking force to act on the hanging door or the like.
Moreover, when the number of revolutions of the drive shaft returns to the initial number, the slide member is energized again to the torque adjustor by the spring means and returns to a state where the torque originally set can be generated.
The slide member comprises a pair of the members arranged respectively radially at both sides of the chamber through the torque adjustor. Because the total area of the outer surface of the slide member which faces the inner periphery surface of the chamber can be taken large, the generated torque can be set high.
Moreoever, the slide member comprises a single member arranged at one side of the torque adjustor in the radial direction of the chamber. Because the total area of the outer surface of the slide member which faces the inner periphery surface of the chamber can be set small, the generated torque can be made low.
The rotary damper according to a 2nd invention, wherein a housing with its inside provided with a chamber, a drive shaft with its basement end housed inside the chamber, a rotary member housed inside the above described chamber axially supported by the drive shaft and a viscous fluid filled inside the above described chamber are provided and a torque is generated by rotation of the above described rotary member,
the rotary damper generating a torque by the rotation of the above described rotary member, wherein the above described rotary member is provided with the basement portion axially integrally rotatably supported by the above described drive shaft, an oscillation member attached oscillatorily to the basement portion and having an outer surface complementary to a part of the inner peripheral surface of the above described chamber, and a spring means interposed between the above described oscillation member and the above described base portion for allowing the oscillation member to oscillate when the force of more than the regular amount acts on the oscillation member, and
wherein by oscillating the above described oscillation member against the above described basement portion by the above described force of more than the regular amount generated by the rotation of the above described drive shaft, the clearance between the outer surface of the oscillation member and the inner peripheral surface of the above described chamber is narrowed, thereby generating a torque.
When the shearing resistance of the viscous fluid by the rotation of the drive shaft becomes equal to or more than the resistance of the spring means, the oscillation portion oscillates so as to generate a rotational torque. When the rotational speed of the drive shaft becomes high temporarily, a high torque can be obtained immediately and, thereafter, as the rotational speed becomes slow, the torque can be reduced as well.
The above described basement portion is extended to both sides radially from an axial support portion attributable to the above described drive shaft and the above described oscillation member is allowed to comprise a pair of members attached respectively to both ends of the above described basement portion. When the oscillation portion oscillates, a total area of the outer surface of the portion can be taken largely so that a generated torque can be made high.
The above described basement portion is extended to one side radially from an axial support portion attributable to the above described drive shaft and the above described oscillation member is allowed to comprise a single member attached to an outside end of the above described basement portion. When the oscillation portion oscillates, a total area of the outer surface of the portion can be taken small so that a generated torque can be made low.